Without limiting the scope of the invention, its background is described in connection with current methods of etching copper.
It has long been known that copper is an excellent metal for use in integrated circuit metallization. Copper exhibits low corrosion, low electromigration and high conductivity. However, copper is not currently easily integrated into integrated circuit fabrication process flows.
Heretofore, in this field, copper has been patterned in a variety of ways. Copper may be plasma etched using a chlorine based etch chemistry at highly elevated temperatures. Ion milling or magnetron etching with argon or chlorine reagents have been somewhat successfully used to pattern copper. Lift-off techniques have been used to pattern copper metal features. Wet chemical etching of copper is also known, as well as dry etching with activated gaseous reagents. Etching can be avoided by selectively eletroplating a copper film onto predisposed regions of a substrate.